Rod connector

ABSTRACT

A rod connector is provided with a rod supporting portion in a part of a connector main body supported to a leading end of a shank portion. A rod pressing portion is provided in a side opposing to the rod supporting portion, and a rod is clamped and fixed by the rod pressing portion and the rod supporting portion. At this time, small convex portions provided in the rod supporting portion eat into the rod.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Applications No. P2002-267299, filed on Sep.12, 2002; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rod connector for supporting a boneconnection rod which connects bones, for example, a breast bone, alumbar vertebra or the like, and more particularly to a rod connectorstructured such that a connector main body supporting the rod freelyswings with respect to a shank portion attached. to an implant, forexample, a screw or the like.

2. Description of the Related Art

As shown in FIG. 1, in a conventional bone connecting method, aplurality of screws (implants) 103 is screwed in to a lumbar vertebrae,and each screws 103 is supported by a rod 105 each other. And aconventional rod connector 107 interconnects the screws 103 and the rod105.

As shown in FIG. 2, the conventional rod connector 107 is comprised of aconnector main body 113 integrally formed in a distal end of a shankportion 109 supported by a head portion of the screw 103. The connectormain body 113 is provided with a rod insertion hole 111 allowing tofreely insert the rod 105 (shown in FIG. 1) and a locking screw 115 forpressure fixing the rod 105.

According to the structure mentioned above, even in the case that aposition of the screw 103 is slightly displaced, it is possible to fineadjust the position of the rod connector 107 by adjusting a position ofthe shank portion 109 and a rotation of the shank portion 109 around anaxis thereof with respect to the screw 103, whereby it is possible toproperly support the rod 105. However, the rod connector 107 can beadjusted with respect to the screw 103 only in a range that the shankportion 109 can rotate. Accordingly, there is a problem that anadjustable range is small.

Further, according to Japanese Patent Application Laid-Open No.11-318932, there is disclosed a structure in which a connection devicecorresponding to the rod connector 107 of the related artmentioned-above is constituted by a plastically deformable member, and arod is properly supported by plastically deforming the connectiondevice.

In this case, there is also a problem that a freedom of adjusting therod connector with respect to the screw is small.

BRIEF SUMMARY OF THE INVENTION

The present invention is made by taking the problems mentioned aboveinto consideration, and an object of the present invention is to providea rod connector in which a position adjustable range is large. To attainthis object, a rod connector according to the present invention iscomprised of a connector main body swingably attached to a distal end ofa shank portion; a rod supporting portion provided in a part of theconnector main body and supporting a rod; and a pressure fixing deviceprovided in the connector main body for pressure fixing the rod to therod supporting portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a connection state of a vertebra bodyby using a conventional rod;

FIG. 2 is a schematic view of a conventional rod connector;

FIG. 3 is a perspective view of a rod connector according to anembodiment of the present invention;

FIG. 4 is a front elevation view of the rod connector according to theembodiment of the present invention;

FIG. 5A is a right side view of the rod connector according to theembodiment of the present invention;

FIG. 5B is a partly enlarged view of FIG. 5A; and

FIG. 6 is a plan view of the rod connector according to the embodimentof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 3 and 4, a rod connector 1 according to anembodiment of the present invention is provided with a shank portion 3having a circular cross sectional shape and supported to a U-shapedengagement groove formed in an upper portion of a screw (an implant) Sbeing screwed into a vertebra body (not shown). A rear end portion ofthe shank portion 3 is provided with a flange portion 5 (a come-offprevention means) for preventing the rod connector 1 from coming offfrom the U-shaped engagement groove of the screw S in an axialdirection.

A connector main body 11 is swingably attached to a distal end portionof the shank portion 3. The connector main body 11 is provided with arod supporting portion 9 having a circular arc curved shape andsupporting a rod 7 for a bone connection connecting vertebra bodies. Inmore detail, the connector main body 11 is comprised of a base bodyportion 11A being vertically attached to the shank 3, protrudingportions 11B and 11C extended from both upper and lower end sides of thebase body portion 11A approximately, and has an approximately C shape.Further, a rod supporting portion 9 is formed on an opposing surface inwhich the protruding portion 11C opposes to the protruding portion 11B.

In order to pressure fix the rod 7 to the rod supporting portion 9, arod pressing member 15 provided with a rod pressing portion 13 having acircular arc curved surface and opposing to the rod supporting portion 9is attached to the connector main body 11 so as to freely move in adirection moving apart from and close to the rod supporting portion 9.

In more detail, a through hole 17 penetrating in a horizontal directionin FIG. 4 is formed in the base body portion 11A, and a base portion 15Aof the rod pressing member 15 is engaged within the through hole 17 soas to vertically move. Further, a spherical body portion 19 formed in adistal end portion of the shank portion 3 is attached to the throughhole 17. Further, a pair of engagement recess portions 21, 21 is formedin each of a portion in which the base body portion 11A of the connectormain body 11 corresponds to the spherical body portion 19, and a portionin which the base portion 15A of the rod pressing member 15 correspondsto the spherical body portion 19 in an opposing manner. The sphericalbody portion 19 is swingably attached to the pair of engagement recessportions 21, 21.

Accordingly, in a state in which the spherical body portion 19 of theshank portion 3 is lightly clamped by the pair of engagement recessportions 21, 21 of the connector main body 11, it is possible to swingthe connector main body 11 in a desired direction with respect to theshank portion 3. On the other hand, when the pair of engagement recessportions 21, 21 firmly clamp and fix the spherical portion 19, theconnector main body 11 is fixed to the shank portion 3.

In order to clamp and fix the rod 7 by the rod supporting portion 9 andthe rod pressing portion 13, and clamp and fix the spherical bodyportion 19 by the pair of engagement recess portions 21, 21, aprotruding portion 11B is provided with a pressure fixing device 23 forpressing and fixing the rod pressing member 15 in a direction of the rodsupporting portion 9. As one embodiment of the pressure fixing device23, in the present embodiment, a fixing screw freely pressing the rodpressing member 15 by a distal end thereof is screwed into the connectormain body 11.

Accordingly, the rod 7 can be fixed and supported by the rod supportingportion 9 and the rod pressing portion 13, by fastening the fixingdevice (the pressure fixing screw) 23, and the connector main body 11can be fixed to the shank portion 3.

In order to fix and support the rod 7, small convex portions 25, 25having a sharp distal end eating into the rod 7 are provided in aprotruding manner in both end sides of the rod supporting portion 9 andthe rod pressing portion 13 (both end sides of the rod 7 in alongitudinal direction), as shown in FIG. 5B. Further, a supportingsurface 9 a is provided between the convex portions 25, 25 of the rodsupporting portion 9 (FIG. 5B shows only the small convex portion 25 ofthe rod supporting portion 9). In the same manner as the supportingsurface 9 a, a supporting surface 13 a is provided between the convexportions (not shown) These supporting surfaces 9 a, 13 a are formed as arough surface, for example, by a sand blast or the like.

Accordingly, when the rod 7 is firmly clamped and gripped by the rodsupporting portion 9 and the rod pressing portion 13, and a stress isconcentrated near a distal end by the sharp distal end of the smallconvex portions 25, so that the distal end of the convex portions 25eats into the surface of the rod 7 so as to generate a scratch, and thesupporting surface 9 a (13 a) of the rough surface is brought intocontact with the rod 7. Therefore, it is possible to prevent the rod 7from moving in the axial direction and it is possible to prevent the rod7 from rotating around an axis thereof.

In this case, in some difference in diameter of the rod 7, there is acase that the engagement state between the engagement recess portions21, 21 in the connector main body 11 and the rod pressing member 15, andthe spherical body portion 19 of the shank portion 3 is slack, at a timeof firmly gripping and fixing the rod 7 by the rod supporting portion 9and the rod pressing portion 13. Further, on the contrary, there is acase that the clamping and fixing state of the rod 7 by the rodsupporting portion 9 and the rod pressing portion 13 becomes slack, in astate in which the engagement state between both the engagement recessportions 21 and the spherical body portion 19 is a firm fixing state.

In the case mentioned above, the rod supporting portion 9 is replaced bythe connector main body 11 formed in the circular arc curved surfacecorresponding to the diameter of the rod 7, and the rod pressing portion13 is replaced by the rod pressing member 15 formed in the circular arccurved surface corresponding to the diameter of the rod 7, whereby it ispossible to simultaneously achieve a clamping and fixing of the rod 7and a fixing and integrally forming of the connector main body 11 withrespect to the spherical body portion 19 of the shank portion 3. Inother words, it is possible to correspond to various rods 7 havingvarious diameters by replacing both of the connector main body 11 andthe rod pressing member 15 with respect to the shank portion 3.

According to the rod connector of the present embodiment, it is possibleto adjust a position of the shank portion 3 in an axial direction withrespect to the screw screwed into the vertebra body so as to fix, and itis possible to adjust swing and rotation of the connector main body 11in a desired direction with respect to the shank portion 3 so as to fix.

Accordingly, even in the case that an adjusting freedom of the rodconnector is large with respect to the screw screwed and fixed to thevertebra and a slight displacement is generated in the screw fixingposition, or even in the case that the rod 7 has a curve, an incline orthe like, it is possible to easily correspond thereto, and it ispossible to always property support and fix the rod 7, so that theconventional problems mentioned above can be solved.

In this case, the present invention is not limited to the embodimentmentioned above, and can be applied to the other aspects. In otherwords, the same effects can be achieved in a structure in which theconnector main body 11 and the spherical body portion 19 can be fixed bya locking screw, the rod pressing member 15 is omitted, and the rod 7 isdirectly pressed to the rod supporting portion 9 by the pressure fixingdevice 23.

1. A rod connector, comprising: a connector main body swingably attachedto a shank, said connector main body comprising a recess configured toengage part of a spherical end portion of the shank, part of saidspherical end portion extending outside of said recess in a directiontowards the shank; a rod supporting portion provided in the connectormain body and configured for supporting a rod; and a pressure fixingdevice for pressure fixing the rod to the rod supporting portion of theconnector main body, wherein the rod supporting portion comprises convexportions at both ends of the rod supporting portion, said convexportions including a first convex portion comprising a sharp distal endprovided at a first end only of the rod supporting portion andconfigured to be embedded into the rod, and a second convex portioncomprising a sharp distal end provided at a second end only of the rodsupporting portion and configured to be embedded into the rod.
 2. Therod connector according to claim 1, said rod supporting portion betweensaid convex portions further comprising a rough surface.
 3. The rodconnector according to claim 1, each convex portion further comprising aconvex surface, and each sharp distal end including a surfacesubstantially normal to said rod supporting surface.
 4. The rodconnector according to claim 1, said rod supporting portion having alongitudinal direction for supporting the rod along the longitudinaldirection of the rod, and each convex portion further comprising aconvex surface projecting in the longitudinal direction of said rodsupporting portion, said convex portions projecting away from eachother.
 5. A rod connector, comprising: a connector main body swingablyattached to a shank, said connector main body comprising a recessconfigured to engage part of a spherical end portion of the shank, partof said spherical end portion extending outside of said recess in adirection towards the shank; a rod supporting portion provided in theconnector main body and configured for supporting a rod; and a pressurefixing device for pressure fixing the rod to the rod supporting portionof the connector main body, wherein the rod supporting portion comprisesconvex portions at both ends of the rod supporting portion, each convexportion comprising a sharp distal end extending in a smooth, continuous,sharp ridge along a circumferential direction of the rod supportingportion and configured to be embedded into the rod.